1. Field of Invention
The invention relates to endovascular stents and more particularly to an improved endovascular stent insertion method to perform sutureless vessel anastomosis.
2. Description of Related Art
With respect to prior vascular anastomosis techniques, end-to-side anastomosis and end-to-end anastomosis are most used techniques. Suture may be either continuous suture or interrupted suture. However, either suture may lead to the problem of anastomosis stricture. There are two causes for this problem. One is technical error. The other is abnormal vascular intimal hyperplasia caused by iatrogenic endovascular injury after suture injuries. Even an experienced surgeon can not avoid a hundred percent the possible adverse results of vascular anastomosis by sutures which may cause further anastomosis strictures.
Improvement of vascular anastomosis techniques had been an issue for vascular surgeons. Surgeons tried whatever they can to decrease the possibility of anastomosis stricture. Some anastmosis methods had been proposed such as applying laser or heat in small blood vessels for a single anastomosis suture and various anastomosis sutures, newly developed variable devices for vascular anastomosis, and applying adhesive materials for blood vessel anastomosis so as to achieve better long term results.
However, no perfect anastmosis technique had been developed yet. There are many problems to be overcome. There is a need for a simple, safe, quick, reliable, and cost effective technique as a replacement of the conventional vascular anastomosis techniques using sutures. This anastomosis method using stent grafts to connect vessels are designed to be applied in peripheral vascular anatomosis.
As shown in FIG. 9, a typical endovascular stent 140 is shown. It is cylindrical (i.e., the same diameter). Hence, it is limited to apply blood vessels with the same diameters.
As shown in FIG. 10, a typical artificial blood vessel 150 is shown. It is elongated and has one end connected to an artery 160 and the other end connected to a vein 170. However, in practice the typical artificial blood vessel 150 may in the long run cause stricture at its junction with a human blood vessel after conventional suture anastomosis. As a result, thromboses may form at the junction stenosis. This may be caused due to the following reasons. First reason is that abnormal growth of epithelial tissues, too much platelets coagulation and subsequent thrombi formation are caused by iatrogenic endovascular injury after surgery. Second reason is that thrombi formation is caused by turbulence formed at the junction of an artificial blood vessel and a human blood vessel due to blood vibration. Third reason is the different degrees of compliance at the junction of the inserted artificial blood vessel 150 and a human blood vessel. As a result, thrombosis is formed due to stricture at anastomosis.
Hence, the typical vascular anastomosis techniques using conventional sutures are disadvantageous. Both typical endovascular stent 140 and artificial blood vessel 150 have a number of problems. Thus, the need for improvement still exists.